1. Field of the Invention
The present invention relates to an image pickup apparatus for use in an apparatus or a system arranged to record a still image or a moving image on a recording medium (such as a flash memory, a tape, etc.).
2. Description of Related Art
A digital still camera (a poly-pixel digital still camera) using a solid-state image sensor which has, for example, two million or more pixels (a poly-pixel CCD) has become available in the market.
The amount of data of an image picked up by a digital still camera increases accordingly as the number of pixels of the CCD used in the camera increases. The amount of data, however, sometimes becomes excessive for purposes, such as image communication or WWW (word wide web), other than printing purposes which require a large number of pixels.
Further, the digital still camera is arranged to record a picked-up image on a recording medium which is disposed within the camera. However, since the recording capacity of the recording medium is limited, the number of photo-taking frames has sometimes happened to decrease, becoming less than a specified number of frames.
To solve this problem, therefore, many of poly-pixel digital still cameras are arranged to have a mode of reducing signals of pixels outputted from the CCD and recording signals of the reduced number of pixels on the recording medium.
Meanwhile, in the case of a digital video camera, such as the so-called DV camera or the like, a signal to be recorded on the recording medium is set by standard specifications to a signal composed of a number of pixels defined by 720 pixels in the horizontal direction and 480 pixels in the vertical direction. If the CCD used in the digital video camera is a poly-pixel CCD, therefore, it is necessary to reduce signals of pixels outputted from the CCD and to record, on the recording medium, signals having the reduced number of pixels conforming to the standard.
Known methods for reducing the number of pixels in a digital still camera or a digital video camera (pixel signal reducing methods) include a method in which signals of all the pixels of the CCD are temporarily stored in a frame memory and, after that, a number-of-pixels converting action is performed by filtering to remove high-frequency components of the signals (hereinafter referred to as the number-of-pixels converting method), and another method in which signals of a necessary number of pixels are extracted from signals of pixels corresponding to a central portion of the image pickup plane of the CCD (hereinafter referred to as the central-portion extracting method).
The conventional image pickup apparatuses, such as the digital still camera, the digital video camera, etc., as mentioned above, however, are individually arranged to fixedly use only one of the number-of-pixels converting method and the central-portion extracting method.
Therefore, it has been impossible to attain a depth-of-field effect or to make effective depiction, etc., as desired according to the situation of photo-taking.